Lesson 6 Flashcards
Life history theory
explains how organisms allocate limited energy across competing biological functions:
- Growth
- Maintenance and immunity
- Reproduction
- Storage
Life history trade offs
Environmental resources are limited, trade-offs between adaptation in one area and adaptation in another
Life cycles
defined as the strategy
an organism uses to allocate its energy
towards growth, maintenance,
reproduction, raising offspring to
independence and avoiding (premature)
death. defined as the strategy
an organism uses to allocate its energy
towards growth, maintenance,
reproduction, raising offspring to
independence and avoiding (premature)
death.
Income breeding
use mainly resources
collected during the period of
reproductive activity
- r selected = more offspring, lower
investment
r = growth rate (reproduction)
Capital breedings
– organisms rely on
resources gained previously and
accumulated for reproductive investment
- K selected = fewer offspring, more
investment
K = carrying capacity of local environment
Fertility
Number of children born
Fecundity
The psychological capacity to reproduce
Fecundity, Fertility, and Energy influenced by
- Cultural norms and practices.
- Energy availability (nutrition, workload).
- Breastfeeding (affects postpartum fertility).
- Disease burden and maternal health.
Human reproduction is adaptive and flexible, responding to environmental and cultural conditions.
Fecundity is sensitive
To energy availability in humans and other great apes
Genotype
The genetic makeup of an organism including specific alleles
Phenotype
The set of observable characteristics or traits of an organism.
phenotypic plasticity
The ability of one genotype to produce different phenotypes in response to environmental inputs.
canalized traits
(brain size) show low plalsticity
plastic traits
(body size) respond fllexibly to envioornmental cues
passive plasticity
direct envinmental effects (undernutrition leads to stunted growth)
active plasticity
develoopmental pathways adapt to predicted future enviornments (e.g., energy allocation in fetus)
menarche
the first menstral cycle timing of pubertyt onset of ferttility
reparing for pregnancy (infancy)
Hypothalamus produces
gonadotropin-releasing
hormone (GnRH)
Causes release of:
Luteinizing hormones
Follicle stimulating hormones
–>
Androgen or Estrogen
Preparing for pregnancy (adolescence)
Gonadotropin-releasing
hormone (GnRH) is
reinitiated by hypothalamus
* Puberty, Development of
secondary sexual
characteristics
* Pelvic size change in girls
DOHaD – Developmental Origins of Health and Disease
Early-life exposures shape disease risk in adulthood:
Maternal malnutrition, stress, or infection can lead to metabolic disorders (e.g., obesity, diabetes, CVD).
barker hypothesis
Low birthweight → increased adult disease risk.
Dutch Famine (1944–45)
Children exposed in utero had elevated risk of chronic illness in adulthood.
thrifty phenotype
A. weather forecast (Bateson) - maternal signaling forecast conditions of childhood, mismatch creates health problems
B. predictive adaptive response (Gluckman and Hanson) fetus predicts its likely future environment and adopts
developmental trajectory to match adult phenotype
C. intergenerational phenotypic inertia (Kuzawa) -variation in birth weight tracks long term phenotype of mother,
grandmother, not short fluctuations
D. maternal fitness (Wells) - Parent-Offspring conflict theory, information received by offspring in utero is not accurate guide to external environments – maternal phenotype buffers, mothers
signal their own development
epigenetics
The study of changes in organisms
caused by modification of gene
expression rather than alteration of
the genetic code itself
* Only a fraction of the genes in a cell
are active / expressed, in terms of
making a gene product
* Epigenetics studies the process of
activation and deactivation that
determine the product of genes
* Nature vs. Nurture is no longer a
debate, both work together to build
an organism
